The present invention is directed to digital video, and more particularly to handling video transition errors in video-on-demand streams.
Video-on-demand is a service which provides customers with the ability to select movies when they desire. The movie is then transmitted from a video rental business in combination with a video server. Utilizing current technologies digital video-on-demand servers usually deliver MPEG-2 transport streams for interactive services such as Pay-per-view, Quasi video-on-demand services, near video-on-demand services, and true video-on-demand services.
Pay-per-view (PPV) services are services which the user signs up and pays for specific programming, similar to existing cable television PPV services. Quasi video-on-demand services are services in which users are grouped based on a threshold of interest. Users can perform at the temporal control activities by switching to a different group. Near video-on-demand are services in which functions like forward and reverse are simulated by transition in discrete time intervals, normally on the order of five minutes. Such capabilities are provided by multiple channels with the same programming skewed in time. True video-on-demand services are services in which the user has complete control over the session presentation. The full-function VCR capabilities, including forward and reverse play, freeze, and random positioning. True video-on-demand needs only a single channel per customer.
To achieve VCR type capabilities, known as trick modes, a set of files for various tasks modes are generated in advance by preprocessing the MPEG data in the video-on-demand servers. For example, the fast forward file is generated by transmission of the I-frames only. The I-frames are transmitted at a frame rate of 10 frames/sec. When playing the fast forward file, although the frame rate is lower, the data rate is the same because I-frames are associated with a greater amount of data.
When a user selects a trick mode, the time base is likely to change. For example, during a fast forward, another video elementary stream is transmitted which is associated with another time base. During transition between the regular play mode and a trick mode, or vice versa, the video server should indicate the discontinuity in the time base to the decoder. Additionally, the video server must calculate time stamps for the other video elementary stream using the other time base. Additionally, after some transitions, a new video elementary stream is commenced starting from a particular picture, such as a return to normal play from pause. If the picture is in the middle of a group of pictures, the video server should indicate the foregoing to the decoder.
However, many preexisting video servers are not equipped to properly handle trick mode transitions. Consequently, the decoders generate a number of errors during trick mode transitions.
Accordingly, it would be advantageous if techniques for handling video transition errors are provided. Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with embodiments presented in the remainder of the present application with references to the drawings.